this seems to be a false positive which happens quite often, unfortunately. I've checked all the file manually using VirusTotal and none of them show a virus using 60+ different engines. Here are the scan results:
Royal TS itself: https://www.virustotal.com/gui/file/9039ae61902bbf7d4f638081ba1a26af7969a1f914ffa578b63c8d817929e5f4/detection
There's not much on our side we can do to prevent that. Most AV tools allow you to submit a false positive once it was verified that no other engine or most other engines do not detect anything. Not sure if Windows Defender has something like that but on my machine, it doesn't flag any of these files. You may check the checksums of the files to verify the file versions you have are the ones from our website.
I'm using v7.0.11221 Beta and as of an hour ago, Windows Defender is flagging the following as Trojans:
containerfile: C:\Program Files\Royal TS V7\RoyalApps.Community.FreeRdp.WinForms.dll
file: C:\Program Files\Royal TS V7\RoyalApps.Community.FreeRdp.WinForms.dll->[MSILRES]